Radio communication apparatus



April 28, 1925.

R. E. THOMPSON RADIO COMMUNICATION APPARATUS Filed March '7, 1919 6Sheets-Sheet l Y LVVENTOR April 28, 1925.

Filed March '7, 1919 6 Sheets-Sheet 2 INVENTOR W Afro/m5);

Ap ril'28, 1925. R. E. THOMPSON RADIO COMMUNICATION APPARATUS eSheets-Sheet 5 Filed March '7, 1919 Arm/vim 6 Sheets-Sheet 4 (A/VENTOA'871 E. THOMPSON RADIO COMMUNICATION APPARATUS Filed March 7, 1919 mum 1mm Haul) April 28; I925.

April 28, 1925. 7 1,535,189

- R. E. THOMPSON RADId COMMUNICATION APPARATUS Filed March 7, 1919 6Sheets-Sheet 5 April 28, 1925.

RADI O COMMUNI CAT I ON APPARATUS Fil' d March '2, 1919 a Sheets-Sheet e74 k l I I g 1z u ii 4 I v I TF I Y I I u 25 l n I Jl/l II [2 l U l 1 2sI a TBA. ,LC EE I A TTORNEY Patented Apr. 28, 1925.

FUNITED STATES PATENT UFFICE.

ROY E. THOMPSON, 0F NFAV YORK, N. Y. ASSIGNOR, BY MESNE ASSIGNMENTS, TO

WIRELESS IMPROVEMENT COMPANY, OF JERSEY CITY, NEW JERSEY, A. CORPORA-TION OF NEW YORK.

Application filed March-7, 1919. Serial No. 231,113.

disclosed the form of the invention which I now consider to be the bestof the various forms in which said principles of the:

invention may be embodiedf} My invention relates to improvements inelectrical circuits or systems, for example, such as are employed inradio communication; and the same has for its object more particularly'to' provide a simple, efiicient and reliable system which may-bereadily tuned.

Further, said invention has for its object to provide a system of thecharacter specified which may be tuned by a single operatio n without.coupling affecting the efficiency of said operation and requiringadjusting.

Further, said invention has for its object to provide a system of thecharacter specitied in which the tuning elements thereof are disposedtherein in non-coupled relation to each other to permit of the jointoperation of said elements to tune the system without coupling affectingsaid operation Further, said invention to provide a system of thecharacter spec-ified in which one'of a pair of coupled circuits thereofis constructed to be substantially non-cui'nulatlve and efficientlyoperative to receive without tuning adplstment therein oscillations fromthe other of said circuits over a range 'of' wave-lengths, and

in which the tuning elements of th tem are disposed in the said other ofthe coupled circuits, and are interconnected to permit of the actuationthereof by asingle .-operation to tune the system.

Further, said invention has for its object to provide a system of thecharacter specifiedin which the tuning elements thereof- -areinterconnectedto permit of. ar operation thereof at W111 by hand ormotor to hasfor its object tune said system over a range of Wavelengths.

Further, said invention has for its object to provide a system of thecharacter specified in which the tuning elements thereof are renderedsuccessively effective in the system to vary the Wave length over a Widerange by a single operation. Further, said invention-has for its objectto provide a system of the character specified including a variableinductance for the longer Wave lengths of .a range of Wave lengths and avariable condenser for the shorter Wave lengths of said rangefln whichsaid inductance and said condenser are rendered successively effectivein said system to vary the wave length thereof by the continuousoperation of a single control or instrumentality.

Other objectswill in part be obvious and in part be pointed outhereinafter.

To the attainment of the aforesaid objects and ends, my inventionconsists in the novel details of construction, and in the combination,connection and arrangement of parts hereinafter mor fully described andthen pointed out in the claims.

In the accompanying drawings forming part of this specification, whereinlike numeans for continuously varying the in-- ductance of an electricalcircuit over a certain period of time, then continuouslyvaryf ing thecapacity of the circuit over another period of time, and continuallyrepeating this cycle of continuous variation of in- 1 ductance and ofcapacity.

Fig. 3 represents" diagrammatically the application of arrangement ofFig. l tosa transmitter of radio signals.

Fig. represents diagrammatically the application of the arrangement ofFig. 1 to a combined, generator and recelver ot radio signals, thegenerator acting as a source ofenergy for receiving incomingsignals bythe well known heterodyne or beat method.

Figs. 6, 7 8,9, and 10 represent a receiver for use in radiocommunication'and designed to physically embody various diagrammaticdisclosures of Figs. 15.

Referring to Fig. 1,F is an inductance coil broken into twoadjacentsections, 1 and 2. Section 1 is provided with taps 3, 4, 5and' 6, thenumber of turns included between taps being one. Section 2 is providedwith taps 7, 8, 9 and contains between taps tour turns, which isequivalent in turns to all the turnsin section 1 plus the turnsincludedbefween two adjacent taps of section 1. D is a switch forbringing into circuit any tap of section 1. Theswitch has four contactpoints 10, the number of contact points being suflicient to-connect toall taps of section 1, including the initial and final tapsh 11 isthe'contact arm, of switch D and is-fixed ona shaft 12. E is a switchfor bringing into circuit any tap'of section 2. The switch has threecontact segments 13, the number of segments being sufficient to connectto all taps of section 2. including i the initial and final taps.- 14 isthe contact arm of switch E and is fixed to a shaft 15.;-

Shafts 12 and 15 are mechanically connected by gears A and B. the gearshaving a ratio otone to three, three being the number of segments ofswitch E. 'Jis a crank attached to shaft 12 for producing continuousrotation of switch arm. 11 and consequently of switch arm 14 thruthe-action otthe gears A and B. H is a condenser connected in serieswith as much of inductance coil F as happens to be. tapped him any time.With the gears A and B as described, contact arm 11 makes a completerevolution clockwise during the time that the contact arm 14 completesits travel over one segment" counter-clockwise. Switch arm 14 must beset on shaft 15 in such angular position that it will always start itstravel over a segment of switch E justwhen switch arm 11 of switch Dstarts its cycle of rotation, i.'e., when switch arm 11 starts travelingover contact point 10 which is connected to the initial tap 3 of section1 of coil F. When switch arm 11 completes its, travel over contact 10which isconnected to the last tap of section 1, it begins itsicycle overagain, passing on to switch contact point 10, and when switch arm 14.has passed over segment 13, which is the final tap, of section 2, itbegins its cycle of operation over-again, passing on to segment 13 whichis the initial tap of section 2. 'The electrical circuit for theposition of the switches, as shown in Fig. 1 follows: Condenser Hconnecting wire 16, initial point'17 of section 2 of inductance coil F,tap 8, segment 13", switch arm 14,.connecting wire 18, switch arm 11.switch point 10", tap 4,section' 1 of inductance coil F, initial point19 of section 1, connecting wire 20, back to condenser H.

Referring to Fig. 2, inductance F, condenser H switch D and crank J areparts similar to correspondingparts in Figr- 1. G is a rotaryvaria-bleplate condenser, the rotary plates 24 of which are mechanicallyconnected to shaft 22. O is a switch for doing two things. During aperiod of time it," connects successively with the taps on section 2 ofinductance F, and during a subsequent period ofjtime t brings condenserG into circuit. The-former occurs when switch arm 21 is in contact withswitch segments 13, 13 or 13, and the latter when it is in contact withsegment 13". Segment 22 is a; common segment for'connecting withsegments 13, 13 and 13 which tap off from section 2 of inductance F.Segment 23 in conjunction with segment 13 bringscondenser G intocircuit. The number of segments of switch 0 and the angles subtended .byeach are determined in the following way. One segment 13 and itscorresponding connecting segment 23 are 'used for bringing condenserGzinto circuit, and the fraction of a circle which segment 13 is tooccupy "is determined by the length of the time condenser G is to bein-circuit as compared with the entire time required for a completecycle of variation of both inductance and capacity. In addition to thecondenser segment 13. there is one segment for each tap of section 2,including the initial and final tap, and the fraption of a circlewhicheach takes up is the angular space unoccupied by the condenser segmentdivided by the number of inductance taps. Switch arm 21 is fixed-toshaft 15. Shaft 12:.shaft' 15 and shaft 22 are mechanically connected bygears A, C and P. The ratio over condenser segment-13. For the specificcase shown in Fig. 2 the ratio of. gears A, G and P is one to four totwo. Connectedwith one set of plates of condenser G is plug 25 forconnectingwith any tap ofseetion 1,- p

the tap to be determined by the quantity of fixed inductance desired incircuit during that part of the cycle of operation in which the capacityof the circuit is being varied.

For the position of the moving parts as shown in Fig. 2,-that part of,the cycle ofoperation in which the inductance F is varied is takingplace, and the electrical circuit is as-followsz' Condenser H,connecting w1re 16, "initial point 17 of section 2,.tap 8, segment 13switch arm 21, segment 22, connecting wire 18,-switch arm 11, contactpoint 10 ,tap 4 section 1, initial point 19 of section 1, connectingavire 20, back to condenser II. If the moving partsgwere in suchposition that switch arm 21 were connecting segments 13 and 23, themoving parts other than switch arm 21 eing as shown in the figure), theelectrical circuit would then be condenser H, connecting wire 16,connecting wire 7, segment 13, switch arm 21, segment 23, connectingwire 26, thru condenser G, connecting wire 27, plug 25, tap 5, section1, initial point 19 of section 1, connecting wire back to condenser H.'4

Referring to Fig.3; inductance F, switch D, switch E, gear A, gearB andcrank .l are parts similar to corresponding parts in Fig. 1. L is an'antenna, M is a signaling device such as a telephone microphoneor atelegraph key, and N is the ground. K is I a means-0f producing highfrequency oscilladevice M which is omitted. In addition,

tions of a frequency determined by the constants in the circuit in whichit is placed.' In

,this case it is the well known evacuated bulb type, commonly known asthe oscillion, pliotron. dynatron or the like, and is placed across ,theantenna end 28 and the ground end 29 of inductance F. Fig. 3 is theexact counterpart of Fig. 11. except that condenser H has been replacedby the capacity of antenna L to the gl ound N, with the addition ofthesignalling device M and the source of energy K.

Referring to Fig. 4, this duplicates all parts shown in" Fig. 3,-ex'ceptthe signaling Fig. 4 contains 'a secondary circuit Q which may be ofthetype shown in my U. S. Patent. No. 1328,9552, filed August-21, 1917.This circuit Q consists of inductance coil R of negligiblysmalldistributed capacity, de-

tector-30 which in this case is shown diagrammatically, telephones 31and bridging condenser 32. The incoming signal comes down aerial L thruinductance 0011 F to urv circuit Q.

Referring to Fig. 5, aside from the secondarycireuit. Q. the rest of thefigu'c has its counterpart in Fig. 2, save that the condenserH of Fig. 2is replaced in Fig. 5 by the capacity of antenna L to ground N. andinductance coil F of Fig. 2 is replaced by inductance coil S, similar toit, except that it is shown in Fig. 5 with more turns in section 1 andsection 2, and section 2 is broken up at, points 33 to get rid of the.so-called dead end effect. Switch D of Fig. 2 is replaced in Fig. 5 byswitch T shown with more contact points, viz., twenty-s1x in number.Switch E of Fig 2 is replaced in Fig. 5 by switch U with more justbefore that division of section 2 to which the particular point inquestion is attached, is brought into circuit; thus point 34 is closedjust before division 35 is brought into circuit.- Whenever a division ofsection 2 is in circuit, all of the points 34 preceding that divisionare closed and all those following are open. The detector circuit Q, isa duplicate of detector circuit Q as shown in Fig. 4,.in accordance withmy said patent.

Referring to Figs. 6, 7, 8, 9 and 10, illus- I trating radio receivingapparatus termed a receiver, the parts already described in previousfigures are designated with like letters and numbers, and unlesssuchpar'ts contain additional unusual electrical or mechanical features;they will not be further described. All of these figures, except Fig.-

. 9 are drawn to approximately the same scale.

The overi'all dimensions of panel 40 are fifteen inches wide, twelve andthree-fourths inches high. one-fourth inch thick. All other dimensionscan be approximately scaled from these. 39 is an insulating panel which,serves as a support for all of the gears, and

switching and indicating mechanism and the condenser. G. 40 is aninsulating panel which forms the front of the receiver and whichsupports some of the auxiliary parts of the receiver, such as bindingposts, etc. 41' is an insulating panel which supports panels 39 and 40,primary coil S, secondary coil R with its accompanying sliding track 37and sliding track supports 42 and 43. 44 and 45 are castings forsupporting the gear' and switching mechanisms. Switch arm 11 ismechanically connected to shaft 12, thru insulator 46. Switch arm 21ismechanically connected with coupling 47 by means of an insulator 48.Coupling 47 is attached to shaft 15 by means of set screw 49, whichenables switch arm 21 to be turned cont i ct at points 33 of section 2of inductan e l iS described in- Fig. 5. It consists. of fivesingle-pole switches 55'and 56, which are ma e to open or'close byaction of an insulating cam 57 attached to shaft 58, which has a spaceon it outside of the-fixed scale for a second scale to beput on the cardafter the receiver is installed in conjunction with the antenna withwhich it is to be used. The receiver is calibrated in connectionwith aparticular. antenna, and 'the second or wave-length scale is then markedon the card. The primary coil S and thesecondary' coil R are shown indetail in Fig. 9, for it is only by proper construction of these coilsto be described that the above described construction of gear andswitching mechanism cam be applied. to a radio receiver .m'the mostpractical and. eflicient manner. 1"ri-' mary eoil S of. this particulgrI'BCGIVGPLJS wound on an insulating form 66 seven.. and five-eighthsinches long by four and oneei'ghth inches diameter. Section 1 is wound(starting from collar62) with a double layer banked winding for fifteenturns, and tap 37 is made. Taps are then made every single turn untilforty lturns are completed, makingtwenty-five. variable turns. Section 2is wound starting from collar 62, and has a double layer banked winding,and taps are takenevery twenty-sixth turn for 9 divisions, making twohundred thirty-four turns in section 2. In addition, the coil is brokenat points 33, which occur at the end of the first, third, fifth andseventh divisions.

The wire used in both sections 1 and 2 is number eighteen 13 8:. S gaugedouble silk covered copper wire. Secondary coil R- is wound on aninsulating form 67 seven and five-.eighths inches long by three. andfive-sixtecnths inches diameter. It is wound with number eighteenB & Sgauge double silk covered copper wire,,spaced its own diameter by meansof twine (not shown) which is'hound between turns. There are seventyturns in the coil. The secondary coil can he slid along its own axis inand out of the primary S by means of handle 79, arm 80 and track 37. Thepurpose is merely to strengthen or weaken signals, when this isdesirable as in the crowded harbors. vThe mechanism for driving thegears is best seen in Fig. 10. J is a hand crank fordriving shaft'12. 63is a beveled gear attached to 68 which is the rear half of clutch AA.The

70 which turns on shaft 71 which is sup-.

ported bycasting 44. The gear ratiowof gear 70 to gear 63 is one to two.Shaft 71 is connected with flexible shaft BB, which is driven by worm 72andgear 73 within gear box Z, the ratio of worm 72 togear 73 being oneto ten- The gears are driven thru coupling 74 by an electric motor Y,the speed of which is eighteen hundred R. P. M. and which run fromcurrent supply 75 thru switch 76 and push button 77. The speed of motorY is controlled by rheostat CC.

,lVith the motor and gears described, shaft 12 turns at the rate ofninety R. P. M. Motor Y and gear box Z are mounted ona common base 78.The-dot and dash line DD, DD represents a table edge. The parts. 7

to the 'lcft are those things which; can be placed under the table or ata. convenient distance. and the parts to the right are those thingswhich are necessary for control and should be near the operator.

By my invention I am able continuously and uniformly to vary thewave-lengths and therefore the tune of a receiving antenna. circuit thruits entire range over and over again by the manual or mechanical turningof a single control. In this manner a radio operator may literally sweepthe ether for radio signals which may be transmitted on anylmown'wave-length, and he may immediately stop at the tune upon which hehears a signal which he desires to receive. The same is true of atransmitting station equipped with my improved device. Signals ofwavelength continually changing from the shortest to the longestgenerally used may be sent out for the purpose of attracting theattention of other stations having ordinary receivers' orhavingreceivers embodying my said invention. By my said invention theunskilled operator may adjust for the transmission or reception of any.wavelength or tune which he maydo slowly or quickly and to any-extent bythe manual operation of the uni-co'ntrohzor he may cause hisapparatus-to travel automatically over and over its entire range.

\Vith my apparatus. or system the'operator may send or receive allwavelengths or tunes when and so long as this is desirable and he mayinstantly stop at any desired tune and exclude all others whenthis'latter is desirable. The advantages will be apparent to thosefamiliar with the radio art.

The feature shown in Figs. 6, 7 and 8 tenna and detector coils in suchreceivers as my invention may be applied to, and-Fig. 9 illustrates anantenna c011 and a detector coil so proportioned as to diameter, lengthand distribution of wire that highly efficient" transfer of energy fromantennacoils S to detector coil R and thence to detector and indicatingdevice is accomplished at all wave-lengths when the antenna coil isvaried from its minimumto its maximum inductance, without changing thefixed position of coil R or any of the constants in circuit therewith.The antenna coil S is designed when connected with an antenna'havingapproximately 1000 micro farads capacityv to give the antenna circuit arange of from 300 to 8500 meters," and the detector coil R will transferthe energy at any of these wavclengths with substantially equal andmaximum eflieiency. Coils for accomplishing this result for any range ofwave-lengths in the antenna circuit may be designed or worked out byreferring to the information given in the specifications forming part ofmy said Patent 1,328,933, filed August 2-1, 1917.

-The dead end cut out switches 5657 of Fig. 6 for opening the coil S atthe points 3% in Fig. 5 donot form any essential part ofmy inventionthes'e switches being comionly used in many knownfreceivers and" beingshown and described here only because they happen to be attached to theparticular receiver-a description of which is being used herein toillustrate one specific application of my invention.

It will be obvious to any one skilled in the art that many' variationsinthe mechanical or electrical construction of apparatus embodying theuni-control features of my invention maybe worked out without departfing from the scope thereof.

v(lther useful purposes to which my invention may be put will occur toone from time to time asfor instance insynchronous radio telegraphywhere both tr ismitter and recciver may have their waveengths constantlyvaried but still be kept substantially in tune by driving theirrespective -uni-control shafts at substantially the same averagespeedlfl Another very desirable use to which my in 'venti-on may be putis made possible by the uni-control feature when used in connectionwiththe motor driving device shown in Fi onds, the operation beingcontinuously repeated. A transmitter sending on a wavelength within thisrange will be quickly noted by the operator using my apparatus at somepoint during the said period of operation of the same. When thetransmitted signal is noted the receiving operator will of coursedisengage the clutch (39 Fig. 10 stopping immediately at or near thepoint where the signal is heard and make any backward or forwardadjustment necessary to secure the best effect by the manual operationof crank J (Fig. 10). This feature will be found of great importance inthat it makes possible the partial or entire removal of the presentwave-length restriction imposed by law upon transmitting stations. Forinstance the act of August 13, 1912, iegu lating radio communicationrequires certain stations to send and receive onthe normal wave-lengthsof 300 and 600 meters to insure the rereption of distress signals and toinsure the proper handling of commercial business. This regulationcauses congestion on these two wave-lengths. lViy said inventionobviatcs the necessity for such a regulation be- .cause the use thereofinsures that the signal will be duly received or noted irrespective ofthe wave-length thereof.

By my invention I therefore hope and expect to make possible the removalof the present national, as well as international restrictions placedupon theuse by transmitting stations for general public service of morethan two wavelengths, (one of, which two wave-lengths must also underthe present law be" used for all distress messages or messages relatingthereto,) and thru this removal I expect to see the. number of messageswhich may be sent and received simultaneously in the same section orradius, without undue interference, increased at least twofold andprobably more. than tenfold.

I claim z -1. A system of the character described comprising anoscillation circuit, a plurality of frequency determining elementstherefor,

manually operable means mechanically intel-connecting said elements topermit of the jointmechanical operation thereof to causea progressivechange in the wave length of said circuit, a motor drive for said means.and means interposed between said manually operable means and said motordrive topermitof the operation atwill by the manual or motor drivenmeans.

2. A system of the character described comprising an oscillationcircuit, a plurality of elements controlling the frequency of said'circuit, and mechanically and electrically interconnected to permit ofthe joint mechanical operation thereof to cause a progressive changeinthe wave length of said circuit, manually operable means for effectingsaid joint operation, a motor drive for the same, and a clutch arrangedto permit of the operation at will by the manual or motor driven means.

3. A system of the character described comprising an oscillationcircuit, frequency determining elements therein, rotatable controls forsaid elements mechanically and electrically interconnected, a rotatableshaft for jointly operating said controls to cause a progressive changein the wave length of said circuit, a gear loosely mounted on saidshaft, power driven means permanently meshing with said gear, a memberon said shaft for manually rotating the same, and a clutch forconnecting said shaft and said gear together to permit of the operationof 7 said shaft by said power driven means.

4. A system of the character described comprising an oscillationcircuit, an inductance therein, a variable condenser in said circuit,mechanically and electricallyinterconnected switches respectively tapped1 to unit sections of a part of said inductance and to multiple sectionof another'part of said inductance, and coordinated to permit of thecycle of operation of the unit switch to be repeated for each stage ofoperation of the multiple switch, means actuated jointly withsaidswitches to progressively vary the] capaclty of said condensereffective in said circuit, and means controlled by the operation ofcertain of saidswitches to out said condenser out of said circuit; allwhereby the operation of said system progressively varies the wavelength of said circuit over a wide range;-

5. A system of the character described comprising an oscillationcircuit,a variable inductance for said circuit, a variable con 'dens'er for saidcircuit, means for actuating said inductance and-said condenser to varythe wave length of said circuit over a wide range by a single operatlon,and means 0p-- erated by said first named means to render saidinductance and said condenser successively effective in said circuit tovarythe wave length of said. circuit over said range.

'6l A system of the character described comprising an oscillationcircuit, frequency determining elements therefor including a Variableinductance and a variable con-' denser, a control for actuating saidelements tovary the wave length of said cireult over a wide range by asingle operation, and means operated by said control to render oneelement inefieetive in said circu1t to varythe-wavelength during theeffective operation of the' other element-to vary said wave length. v 1

certain of said switchesto render said inductances and said condensersuccessively effective ,in said circuit to vary the wave length thereof.

8. A system of the character described comprising an oscillationcircuit, a variable inductance therefor, a Variable condenser for saidcircuit, means mechanically interconnecting said inductance and saidcondenser to permit of the variation of the wave length of said circuitover a wide range by a single operation, and means controlled by saidfirst named means to disconnect said condenser from the circuit duringthe effective variation of'saidinductance in said circuit, and toprevent the varia tion of said inductance during the effective operationof said condenser to vary the wave length of said circuit. 1

0. A system of the character described comprising an oscillationcircuit, a variable element therein to permit of'the variation of thewave length of said circuit by small degrees over a part of the wavelength range thereof, a variable element therein to permit of theprogressive variation of the wave length of said circuit over theremaining part of said range,-means mechanically interconnecting saidelements to permit of the variation of said wave length over said rangeby a single operation, and means operated by'said first nameduneans torender one element ineffective insaid circuit to ing said several n10able pa ts. to permit of the variation of the wave length of saidcircuit over a range by a single operation. and a secondary circuicoupled to said aerial circuit, and constructed to be sul sta'ntiallynon-cumulatife and efiicicntly operative to receive. without tuningadjustment therein and at definite coupling the. oscillations from saidacrial circuit of the several wave lengths of said range.

other to vary the wave length for the system asa Whol'eby the jointoperation of said elements'without coupling affecting the elii- 'cieucyof said operation and reqiiiring ad'- justment, a plurality ofadjustable trequeucy determining elements for said circuits includingrelatively movable parts to. permit of the variation of the 'wave lengthfor the system vas. a whole by the joint operation of said elements; allof said jointly operableelements being soarranged relatively to saidinterlinkiug means as to dispose said elements in non-coupled relationto each other in said circuits to permit of the. said joint operation ofsaid elements without coupling ati'ecting the eflieiency of saidoperation and requiring adjustment, and a single control mechanicallyinterconnecting said several n'iovable parts tor aitcct- 1 ing saidjoint operation of said elements to vary the wave-length for the systemas a whole.

12. A system of the character described comprising an aerial circuit, anadjustable inductance therein, an adjustable condenser in said circuit,acontrol mechanically interconnecting said inductance and said condenserto permit of the variation of the Wave length of said circuit over awide range by a single operation, means operated by said control torender said inductance and said. condenser successively eil'ectiveinsaid cir- 40 cuit to vary said wave length, and a secondary circuitcoupled to said aerial circuit, and constructed to besubstantiallynoncumulative and'e'tliciently operative to receive Withouttuning adjustment therein the 4 oscillations from said aerial circuitofthe several wave lengths of saidrangc.

153. A system ofthe character described comprising an aerial circuit, aplurality of inductauces therein to permit of the variation of the Wavelength of said circuit by small degrees over a part of the rangethereot, a variable condenser therein to per mit ot the progressive.variation of the Wave length of saidicircuit over the remaining part ofsaid range, means mechanically interconnecting said inducta -rces andsaid condenser to permit of thejoint mechanical operation there'otto'vary. the wavelength of said circuit over said range by a single op-69 eration, means operated by said first named means to rendersaidinductanccs and said condenser successively effective-in said circuit tovary the wave length over said range, and a secondary circuit coupled tosaid i aerial circuit, and constructed to be substantiallynon-cunnilative and eliicicntly operative to receive ivithout tuningadjustment therein the oscillations from said aerial cir-. cuit of theseveral wave lengths of said range.

14. A system of the characterdescribed comprising an oscillationcircuit, a variable inductance for said circuit; a variable con denserfor said circuit, manually operablev means for actuating said inductanceand said condenser to vary the wave length. of said circuit over a widerange by asingle opera tion, means controlled by said manually operable,means to render said inductance and said condenser successivelyefi'ecti've in said circuit to vary the said Wave length over saidrange, amotor drive for said manually operable means, and means topermit of the operation at \vill by the manual or motor driven means. iA

15. A system ot the character described comprising an oscillationcircuit; a plurality of variable inductances therein to permit of thevariation of the Wavelength of said circuit by small degrees over 'apart of the range thereof, a variable condenser therein to permit of thevariation of the Wave length of said circuit over the remaining part ofsaid range, manually operable rotatable.

means mechanically interconnecting said inductances and said condenserto permit of the variation of the wave length of said circuit over saidrange by a single operation,

means controlled by said-manually operable means torender saidinductances and said condenser successively effective in said circuit'tovary the said wave length over said range, a motor drive torn saidmanually operable means, and means to permit of the operation at will bythe manual or motor driven means. G73

16. A system ot'the character described comprising an oscillationcircuit, a variable inductance therein, a variable condenser in saidcircuit, manually operable means for actuating said inductance and saidcondenser to vary the Wave length of said circuit over a wide range by asingle operation, means controlled by said manually operable means fordisconnecting said condenser from said circuit during the variation ofsaid inductance, a motor drive for said manually" operable means, andmeans to permitof the operation at'ivill by the manual or motor drivenmeans.

17. Asystem ot' the character described comprising an aerial circuit, aplurality of frequency determining elements therein hav ingrelativelymovable parts, manually operable' means mechanically interconnectingsaid several movable parts to permit of the variation of the Wave lengthof said circuit progressively over a range by a single operation.a-secondary circuit coupled to said aerial circuit, and constructed 'tobe substantive to receive without tuning adjustment thereinand-atdefinite coupling the oscillations from said aerial circuit of theseveral wave-lengths of. said range; a motor drive for said manuallyoperable means, and means to permit of, operation at will by the manualor motor dr ven means." l.

18. A system of the, character described comprising an aerial circuit,avariable inductance therein, a variable condenser therein, manuallyoperable rotatable means mechanically interconnecting, said-inductanceand said condenser to permit of the joint mechanical operation thereofto vary the wave length of said circuit over -a wide range, meanscontrolled by said manually amu operablemeans to render said inductanceand said condenser successively effective in said circuit to vary thewave length over said range, a secondary circuit coupled to sald aerialclrcuit, and constructed to be substantially non-cumulative andefficiently" operative to receive Without tuningadjustment therein theoscillations from said aerial circiiit of the several wave lengths ofsaid range, a mozor drive for said manually operable means and means topermit of the OTTO A. MARTINI, J ULiAN BARTH.

